1. Field of Invention
The invention relates to a pneumatic tool structure and, in particular, to a pneumatic tool with an improved soundproof device.
2. Related Art
The operation principle of a pneumatic tool is to use a high-pressure gas to drive the pneumatic motor therein. Therefore, the pneumatic tool has to have a gas inlet for a gas to enter and a gas outlet for it to leave. Normally, the gas outlet of a pneumatic tool is designed to guide the gas out from the back or from one side. However, there is usually a loud noise when the gas directly leaves the pneumatic tool.
For the design of releasing gas from the back, as shown in FIG. 9, the gas is blocked by the supports 4 between the ventilation holes 2 in the back of the pneumatic tool 1 as it escapes, resulting in turbulences and noises. Moreover, the gas expelled from the back of the pneumatic tool 1 directly hits the quick connector 3 on the back of the pneumatic tool 1. This further increases the noises and produces high-pitched sounds.
FIG. 10 shows a conventional pneumatic tool 1A with side ventilation holes. Indeed, it can avoid the exhaust gas from directly impacting the quick connector (not shown) connected to the rear end of the pneumatic tool. However, the ventilation holes 2A are formed in a matrix form. Therefore, when all the gas leaves via the ventilation holes 2A, there are still collusions between the gas molecules and the supports 4A between adjacent ventilation holes 2A, producing turbulence and high-pitched noises.
In practice, one usually adds silencer cotton to the pneumatic tool whether the gas leaves from the back or the side. However, tests show that the noise intensity can only be reduced to around 82 decibel (dB). Therefore, the prior art still cannot effectively reduce the high-pitched noises produced by the exhaust gas. It is therefore an objective of the invention to solve this problem.